A common way for implementing SSL with EC2 is by terminating SSL at load balancer level.
This way, the request from outside is transported via HTTPS until it reach Load Balancer, and then it uses normal HTTP protocol to reach web server instances.

Today we had task to use SSL to secure our REST service API. We use sitewide certificate purchased from GoDaddy.
Thanks to this article we managed to do it.

To apply the same certificate to IIS, we need to convert the certificate to .pfx first

openssl pkcs12 -export -out certificate.pfx -inkey private.pem -in certificate.crt -certfile intermediate.crt

The private.pem in the above message is the private key, certificate.crt is the certificate file and intermediate.crt is intermediate certificate if any. The output is certificate.pfx which can be imported by IIS.
The above information is taken from this article